Is it possible to make a copy of a thread in .Net? Kind of like a fork() but on just a thread instead of the whole process?
I have a recursive algorithm, and for testing purposes I wan't to evaluate several different branches that the code can take. The easiest way would be to clone the thread at the decision point in the code and let each thread continue in a different branch.
I have got this module which copies a specific folder and all files inside it.[code]...
View 8 RepliesIn one application, I need use 4 simultaneous threads.When the threads finished, I need to update the text of a TextBox.So, I create 4 Textbox, and I wanna the threads change the text to FINISHED.Each thread change one distinct TB.I use this "example"
Dim Terminados As Integer = 0
Private Sub frmEnviarMensagem_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Timer1.Enabled = True
Timer1.Start()
[code]....
The problem is, I have an error in the red lines.The error is: INVALIDOPERATIONEXCEPTION "Cross-Thread operation not valid: Control tbPlaca1 Accessed from a thread other than the thread it was created on."I don't use cross threading. Each TB only was accessed for the correspondent thread, and for the "main program".
This is the error message I am getting:
"Cross-thread operation not valid: Control 'Panel1' accessed from a thread other than the thread it was created on." The reason I am getting this error is because I am opening up a new form and then calling these three things:
Panel1.Show()
Label1.Show()
Label2.Show()
why I get this error message because it doesn't occur normally if I open Form2 after closing Form1, it only occurs when I open Form2 after closing Form4.
I have done a program using vb2005 to display reading from my microcontroller bs2 board but have encountered some problems. My code are as follows.
Dim Stop_Rx As Boolean
Private Sub btnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnRead.Click
SerialPort1.Open()
[code]....
I've encounter an error which is, (Cross-thread operation not valid: Control 'txt1' accessed from a thread other than the thread it was created on.)
When my client try to connect to server I'm getting this error : Cross-thread operation not valid: Control 'l_users' accessed from a thread other than the thread it was created on.
Private Sub _socketManager_onConnectionAccept(ByVal SocketID As String) Handles _socketManager.onConnectionAccept
l_Users.Items.Add(SocketID)
End Sub
Would anyone be able to help me here please. I'm fairly new to VB.net and threading so im just trying to figure out what is happening.When I debug this I am getting the error thread operation not valid: Control 'ProgressBar1' accessed from a thread other than the thread it was created on.
I'm a little lost as to why the error is occuring or how to fix it. I've had to put the progress bar in a separate thread otherwise the GUI crashes
[Code]...
My understanding is that thread.join will suspend the execution of code on the calling thread until the spawned thread finishes or is aborted...
With that in mind, I tried this:
For i = 1 to 50
threads = New Thread(AddressOf test)
threads.IsBackground = True
threads.SetApartmentState(ApartmentState.STA)
[CODE]...
However, the rest of the code runs when the loop finishes, not waiting for all the spawned threads to finish. Since the rest of the code needs the threads to finish (otherwise the rest will error).
I have written an application that loads a form - frmCad as well as AutoCad. It does this via a class which detects when AutoCad quits.
Friend Class CadApp Private WithEvents AppObject As AcadApplication... Private Sub AppObject_BeginQuit(ByRef Cancel As Boolean) Handles AppObject.BeginQuit RaiseEvent Quit() End SubEnd Class
My main class loads frmCad as well as CadApp.
Public Class Cad Private WithEvents frmCad As CadForm Private WithEvents app As CadApp... Public Sub ShowForm() If frmCad Is Nothing Then frmCad = New CadForm frmCad.Visible = True End Sub... Private Sub app_Quit() Handles app.Quit frmCad.Dispose() frmCad = Nothing .... End Sub
When I debug the program, it stops at frmCad.Dispose()The program continues to execute, but all the code after it fails to work.Looking more carefully I get an error message which contains:-Cross-thread operation not valid: Control 'Autocad' accessed from a thread other than the thread it was created on.
My error:Cross-thread operation not valid: Control 'label2' accessed from a thread other than the thread it was created on. I want to be able to give my Public RunBot() sub access to edit Labels, buttons, etc without an error.
[Code]...
I'm getting the 'System.InvalidOperationException' error on acccessing a thread from other than where it was created. My code is:
'Required by the Windows Form Designer
Public components As System.ComponentModel.IContainer ' changed from private
[code]....
My problem is Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on.
System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'statusHO' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
StackTrace:
[Code]...
i used it and it works fine then. but as it is mentioned its not a good practice to use it. So what should i do? is it ok if i use this as i am not able to use correct practice. Mine application is not for enterprise purpose. its just my class project, and it works fine even if i put application working in background. System works ok. I dont know how to correct this error.As i dont have that much knowlege of threads.
So please guide me how to fix this in correct way otherwise i am force to go for bad programming practice
Please refer to Windows Mobile Developer Center > Smart Device Development Forums > Windows Mobile Development > Appendtext not working for all my code details
Cross-thread operation not valid: Control 'lv1' accessed from a thread other than the thread it was created on.
Dim lvi As ListViewItem
For Each lvi In lv1.Items
[code]....
I have an application in which I am running a separate thread.
Dim thread As New System.Threading.Thread(AddressOf Main)
thread.Start()
However, the thread makes reference to an textbox named Output, and it generates this error upon execution:
System.InvalidOperationException was unhandled
Message="Cross-thread operation not valid: Control 'Output' accessed from a thread other than the thread it was created on."
Source="System.Windows.Forms"
(message shortened for space)
How can I make the operations run on another thread, but still use the Output object? I cannot call a subroutine to do that for me, as it generates the exact same error.
The method called is AppendText, by the way.
Ok i have a Form with the following
Private Sub frmMain_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
txtNotepad.Text = LoadFile("notes.txt")
[code].....
i have a timer and i want its calculation will be done on another thread, since the timer tick event start whenever its enable property is set to true i don't see how to force it to work in another thread.
View 6 RepliesI'm currently making a bot that points and clicks. It works great! The only problem I have is stopping the bot.How could I make a shortcut key that stops the bot while it's running?
View 14 RepliesHow do I make a subroutine (LoadIntro()) execute on another thread?
View 6 Repliesi got a background worker that has the following code in the do work.... one of the things i want to do is to add rows if theres none available ...but i got an error saying i need to do a safe call thread...i already read about it but im stuck i put control.invoke, but that gives me an error too saying Error 1 Reference to a non-shared member requires an object reference.
[Code]...
I am trying to make a thread-safe call to a button on another form and I cannot figure out how to do it.I have read all of the MSDN documentation on thread-safe calls .
View 10 Repliesi got a background worker that has the following code in the do work.... one of the things i want to do is to add rows if theres none available ...but i got an error saying i need to do a safe call thread...i already read about it but im stuck i put control.invoke, but that gives me an error too saying Error1Reference to a non-shared member requires an object reference.what can i do to add rows safely?
vb.net
Private Sub BackgroundWorker2_DoWork(ByVal sender As System.Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker2.DoWork
If DataGridView2.Rows.Item(num).Cells.Item(0).Value = "" Then
Control.Invoke(DataGridView2.Rows.Add(1))
[URL]
In my program, I created a list of a class that contains 5 picture boxes, a button, a label, an identifier, and some other stuff. I've got roughly 65 of these in this list. I'd be stupid to hard code all that in. The identifier is a 2nd way of identifying which specific location I'm working on.
Anways, all this is created at compile time. Works perfectly fine.
I then manually start a background worker that pings a collection of components. Based off the success of those pings, the picture boxes are enabled or disabled. Basically a proactive way to see if a collection of devices over multiple locations are actually working.
It's the background worker that fails because of thread-safe calls.
Private Sub bgwStatus_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles bgwStatus.DoWork
Dim status As Integer
[Code].....
This is my code..this code will copy from destop to device. this code only can copy a file only..it is possible to copy 1 folder?
Imports OpenNETCF.Desktop.Communication
Imports System.Diagnostics.Process
Dim WithEvents rapi As New RAPI
[CODE]...
How can I copy a picture when the program (Visual Basic 10 Express Edition)
runs? The picture is a JPEG image in a picture box. In some basics there are instructions such as GET and PUT. Is that possible in VB? I looked at the answers about pictures in the Forums but I didn't find an answer applicable to VB 10
How can I copy form and make identical form
say want to copy the style of one form & coding and make identicel form 2
How can I copy file and make it hidden .... I want to make file when the user click on create I want to copy file and make it hidden ....
View 2 Repliesi wonder how to make a copy code in my vb 2008 express edition
View 2 Replieswe highlight some texts in a richtextbox.and then we click right click and there will be appear some choices such as:copy,cut,paste etc. make the example of the program i mean?i mean just a simple program.
View 10 RepliesWhen I use the code below, I can't get any (copy)effect as I drag things onto the picture box(img). Therefore, I can't dragdrop files. How can I make dragdrop event possible?
[Code]....
i have been lookin for a refrence on how to get form to make a copy of itself on a button click. without having to make multiple forms in my project. like say i want to open 6 forms and want them to be the same as form 1 i wouldnt want to have to make 6 diffrent forms in my code just to that.
View 6 Replies
